1. Field of the Invention
The present invention relates to an image-forming apparatus and a method for controlling the image-forming apparatus.
2. Description of the Related Art
Known multi-function apparatuses, capable of copying documents, transmitting and receiving image data, and carrying out a printing process in accordance with image data, have many features for reducing power consumption.
For example, a method for dividing the power supply used to supply electrical power to the multi-function apparatus mainly into a power supply for a control system and a power supply for a printing system has been proposed (Japanese Patent Laid-Open No. 2000-318265). In this case, the power supply for the control system continuously supplies power, whereas the power supply for the printing system is turned on and off in accordance with the operation mode of the multi-function apparatus. The operation modes include a print mode in which power is supplied to the printing system and a stand-by mode in which power is not supplied to the printing system.
A known multi-function apparatus is connected to a sheet-processing apparatus that is capable of processing a printed sheet in various ways. Sheet processing includes, for example, sheet post-processing (stapling and punching), sheet-ejection, and sheet conveying.
In a multi-function apparatus connected to a plurality of sheet-processing apparatuses, the same electrical power control is used for both the plurality of sheet-processing apparatuses and the printing system. Thus, the power supply of a multi-function apparatus supplies electrical power to the sheet-processing apparatus in printing mode and does not supply power to the sheet-processing apparatus in stand-by mode.
In most cases, a known multi-function apparatus connected to a plurality of sheet-processing apparatuses only operates a predetermined sheet-processing apparatus and does not operate the other sheet-processing apparatuses. However, in the printing mode of a known multi-function apparatus, electrical power is supplied to all sheet-processing apparatuses connected to the multi-function apparatus. Therefore, extra electrical power is consumed by sheet-processing apparatuses not operated in the printing mode.